<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="lib/vue.js"></script>
</head>

<body>
    <div id="app">
        <input type="text" v-model="n1">

        <select v-model="opt">
            <option value="+">+</option>
            <option value="-">-</option>
            <option value="*">*</option>
            <option value="/">/</option>
        </select>

        <input type="text" v-model="n2">

        <input type="button" value="=" @click="calc">

        <input type="text" v-model="result">
    </div>
    <script>
        var vm = new Vue({
            el: "#app",
            data: {
                n1: 0,
                n2: 0,
                result: 0,
                opt: "+"
            },
            methods: {
                calc() { //计算器算数的方法
                    // 逻辑：
                    // switch (this.opt) {
                    //     case "+":
                    //         this.result = parseInt(this.n1) + parseInt(this.n2);
                    //         break;
                    //     case "-":
                    //         this.result = parseInt(this.n1) - parseInt(this.n2);
                    //         break;
                    //     case "*":
                    //         this.result = parseInt(this.n1) * parseInt(this.n2);
                    //         break;
                    //     case "/":
                    //         this.result = parseInt(this.n1) / parseInt(this.n2);
                    //         break;
                    // }

                    // 注意：这是投机取巧的方式，正式开发中尽量少用
                    var codeStr = "parseInt(this.n1)" + this.opt + "parseInt(this.n2)";
                    this.result = eval(codeStr);
                }
            }
        });
    </script>
</body>

</html>